A convenience store sold chicken, peanut butter and jam sandwiches. The ratio of the number of chicken sandwiches made to the total number of sandwiches made was 1 : 2. The ratio of the number of peanut butter sandwiches made to the total number of sandwiches made was 1 : 9. After the store sold some chicken sandwiches and made another 19 peanut butter sandwiches, there was an equal number of chicken, peanut butter and jam sandwiches left. Find the number of chicken sandwiches sold.
|
Chicken |
Peanut Butter |
Jam |
Total |
Comparing chicken to total |
1x9 |
|
|
2x9 |
Comparing peanut butter to total |
|
1x2 |
|
9x2 |
|
9 u |
2 u |
7 u |
18 u |
|
Chicken |
Peanut Butter |
Jam |
Total |
Before |
9 u |
2 u |
7 u |
18 u |
Change |
- 2 u |
+ 19 |
No change |
|
After |
1x7 = 7 u |
1x7 = 7 u |
1x7 = 7 u |
|
The total number of sandwiches is the same at first. Make the total number of sandwiches the same. LCM of 9 and 2 is 18.
Number of jam sandwiches remains the same at first and in the end. Make the number of jam sandwiches the same. LCM of 1 and 7 is 7.
Number of jam sandwiches
= 18 u - 9 u - 2 u
= 7 u
Number of chicken, peanut butter and jam sandwiches is the same in the end.
Number of peanut butter sandwiches = 2 u + 19
2 u + 19 = 7 u
7 u - 2 u = 19
5 u = 19
1 u = 19 ÷ 5 = 2
Number of chicken sandwiches sold
= 9 u - 7 u
= 2 u
= 2 x 2
= 4
Answer(s): 4